Sure, maybe Sera was an unreliable narrator, and it’s just the USS Relativity working in the background to correct things (even if they end up happening a few years off from when they should).
But maybe in the time scale of millennia, it more or less evens out.
Khan comes to power later in the timeline, but DIS and SNW seem a little more modern than they should? Some things are slowed down, and others are sped up.
I wonder if it’s really time healing itself, or someone healing time.
Taking the idea of temporal wars and a department of temporal investigation to its logical end, it’s like what they said in the second Bill and Ted movie. Only the winner can go back and change things. We can speculate that, at some point in time, the most powerful time-traveling organization possible exists and is actively trying to maintain the meta-timeline that leads to its existence.